Complex phosphate ester synthetic lubricant



Patented Man 24, 1953 UNITED STATES PATENT" carries.

GOMPLEX'PHOSPHATE ESTER SYNTHETIC LUBRICANT Paul V Smith, .11, ,Wes'tfield, and-Fred Kiioth, Jr'z, Union; N; J assifgnors to Standard OiI Bevel--- opment Company, a" corporation of Delaware No Drawing? Application December-29,1948, Serial N 0. 68,083

Thissinvention; relates: toxa new" classof com.-

pounds whichhave been foundto be particularly,

suitable for use. as. synthetic I lubricants because of their low pour points, high viscosity indices,

and exceptional-load carrying, capacities;

In the lubricant art,. considerable progress has 1 been realized in recent years in: the! production of lubricants: characterized by one: or more:

specificv properties and adapted for. particular" uses: In themain,.thisprogresscanbezattributed: to; two developments; the first, new refining;

procedures, and the; second, addition agents;

capable: of imparting particular properties to available lubricants; Thus, viscosity index im--- provers and pour. point depressantsareadded to automotive lubricants to render the vlubricants' morei adaptables to: wide: changes-21m temperature conditionsawhileaother agents-' are added to im prove:the load carryingpropertiesot. alubri-canta is't'o be employed, for example; underrex treme pressurei conditionst Recently, in an effort to obtain StIperlOr fIflbrf cants endowed with specific and superiorchar-- acteristics; a new-field has been' explored, namely, the synthesis of-lubricants from'various materials." Esters represent one class of materials which have-attracted unusual interest as synthetic" lu-- bricants;.. In general, they arecharacterized-by higher viscosity indicesand lower pourpoints thanmineral oils'of corresponding viscosity. The

esters described in the present specification-have been found to exhibit 'very low pour points and high viscosity indicese Lubricants-- possessingsuchspropertiestareof: speciaLvalue in the: lubrication: of engines: which are subjected tohigh temperaturesisuclras combustiomturbineengines; particularly. those: or: tha prop-jet!" type: Mineral oilv lubricants containinggadded viscosity index improvers, ,thickeners or'xother highly'gxnon volatile additives are undesirable-ifor. use in such engines because of the tendency to leave aresidue: which accumulates and interferes. with the I oper*-; ation. of theeng-ine. A=synthetic lubricant of the type described. in the present specification is;

especially. adapted to useeunder suchconditions,

since thelubricantcontainsno additives 'andthusa useful aselubricantswhere ahigher viscosity; oil:

. istrequiredt The new compounds. ofl the-present. invention may be more particularly defined 'by the formula 0R; o' e' o Ra 25 Q/ 0:240 Rs.

Inthis' formula- R represents a-glycolradica1and mayconsistof'a saturated ali hatic hydrocarbon group", straight chain or'br'a'nched, containing? to 18 carbon atoms; orit'may'beaseriesofsatu rated aliphatic hydrocarbon ra',dical's linked" by oxygen or sulfur-atoms, or by both oxygenand sulfur atoms, provided thereare'at least 2*car'- bon atoms between each phosphate" group and the nearest oxygen or sulfur atomancFat'IeaStZ" carbon atoms between each pair-of oxygen and/or sulfur atoms in the chain, and provided bfurtherthat the total number of carbon, oxygen-and sulfur atoms in the entire radical is from Mesa and the number of sulfur atomsi-isi'not greater than 2. R1, R2, R3, and R4 of thepformulaeach represent a monohydric alcohol residue? which may be a saturated or unsaturated: aliphatic hydrocarbon radical; either straight chain or;

branched, containing 1 to 20 carbon atoms, or it may be a series of saturated aliphatic hydrocarbon radicals, straight chain or branched, interlinked by oxygen or sulfur atoms, or both oxygen and sulfur atoms, the total number of carbon, oxygen and sulfur atoms being from 4 to 20. The maximum number of oxygen and/or sulfur atoms in each of these radicals is not greater than 5, of which not more than 2 are sulfur atoms, and there is a chain of at least 2 carbon atoms between the phosphate group and the first oxygen or sulfur atoms in the chain and a similar chain of at least 2 carbon atoms between each pair of oxygen and/ or sulfur atoms in the radical. The radicals R1, R2, R3, and R4 may be alike or different in the same molecule. In order to obtain a compound possessing desirable lubricating qualities it is desirable to choose organic radicals which will produce a compound having a molecular weight of at least 300. 7

Complex esters of the type described above may be conveniently prepared by reacting 2 molecular proportions of phosphorus oxychloride with 1 molecular proportion of a glycol and subsequently reacting the partial ester thus formed with 4 molecular proportions of a monohydric alcohol or of a mixture of such alcohols. The

reactions with phosphorus oxychloride may be brought about by contacting the reactants in the presence of an inert liquid medium at a temperature which should be kept at least as low as about 10 C. to prevent the reaction from becoming violent, after which it is desirable to raise the temperature of the reaction mixture to at least 75 C. for a period of at least two hours to complete the reaction.

The glycols employed in preparing the esters of the present invention include ethylene glycol and any of the parafiinic homologues of the same containing up to 18 carbon atoms. These may include, for example, ethylene glycol, propylene glycol, butylene glycols, pinacone, trimethylene glycol, tetramethylene glycol, pentamethylene glycol; and the like. Since the glycols may also contain oxygen or sulfur atoms, compounds such as diethylene glycol, triethylene glycol, the polyethylene glycols of'the formula HOiCHzCHzO) nonzoiizoir Where n is 1 to 26, and the polypropylene glycols of the general formula R1 R R1 R2 HmcH-oHonoH-oHoH where either R1 or R2 is a methyl group and the other is hydrogen and Where n is 1 to 20, may likewise be employed. Glycols containing sulfur atoms in thioether linkages may also be employed, and-these include Such compounds as thiodiglycol and 1,2-bis(Z-hydroxyethylmercapto) ethane. There also may be used glycols containing both oxygen and sulfur in similar linkages; such a compound is bis-[2-(2-hydroxyethoxy) ethyl] sulfide.

Themonoh'ydric alcohols employed are typified by the following;

Methyl alcohol Ethyl alcohol n-Butyl alcohol n-Hexyl alcohol n-Octyl alcohol 2-ethylhexyl alcohol Cetyl alcohol Oleyl alcohol Ethylene glycolmono-n-butyl ether Ethylene glycol mono-2-ethylbutyl ether Ethylene glycol mono-2-ethylhexyl ether Ethylene glycol mono-iso-octyl ether p-n-Butylmercaptoethanol c-tert-Octylmercaptoethanol pnDodecylmercaptoethanol Diethylene glycol mono-n-butyl ether Diethylene glycol mono-2-ethylbutyl ether Diethylene glycol mono-2-ethylhexyl ether Propylene glycol mono-butyl thioether Propylene glycol mono-tert.-octyl thioether Propylene glycol mono-n-dodecyl thioether n-Butylmercaptoethoxyethanol tert.Octylmercaptoethoxyethanol nDodecylmercaptoethoxyethanol nButylmercalptopropoxypropanol tert.Octylmercaptopropoxypropanol n-Dodecylmercaptopropoxypropanol Propylene glycol mono-n-butyl ether Dipropylene glycol monomethyl ether Dipropylene glycol monoethyl ether Dipropylene glycol mono-n-butyl ether Tripropylene glycol monomethyl ether Tripropylene glycol monoethyl ether Tripropylene glycol mono-n-butyl ether Propylene glycol monoisopropyl ether Dipropylene glycol monoisopropyl ether Tripropylene glycol monoisopropyl ether Many of the above listed ether alcohols, formed by the reaction of ethylene oxide or propylene oxide with aliphatic alcohols, are known in the industry as Dowanols, Carbitols, or Cellosolves.

A group of alcohols especially adapted for use in connection with the present invention are the so-called oxo alcohols, prepared by the reaction of carbon monoxide and hydrogen upon the olefins obtainable from petroleum products and hydrogenation of the resulting aldehydes. Materials such as diisobutylene and C7 olefins are suitable for this purpose; also higher molecular weight olefinic materials are sometimes employed. The alcohols obtained in this manner are primary alcohols and they normally have a branched chain structure.

If desired, various addition agents may be incorporated in the esters of the present invention for the purpose of improving their properties with respect to their usefulness as lubricants. For example, antioxidants, viscosity index improvers, thickeners, pour depressants, dyes, etc.,

may be added.

Data will be given below showing the properties of six examples of complex phosphate esters within the scope of the present invention indicating the adaptability of these esters to lubricating service. All of these esters were prepared by a chain method which was carried out in detail as follows: In a 1-liter round bottomed reaction flask, fitted with a reflux condenser, was placed a charge consisting of 102 grams (0.66 mol) phosphorus oxychloride, 174 grams (2.2 mols) pyridien-e and ml. benzene. The mixture was cooled to l0 C. and 0.33 gram mols of the glycol was added dropwise at such a rate that the temperature never exceeded 10 C. After the addition was complete the mixture was stirred for a few minutes, cooled to -10 C., and 1.40 gram mols of the rn-onohydric alcohol added dropwis-e, keeping the temperature below 10 C. The mixture was then refluxed for two hours, 300 ml. of water added, and the benzene layer separated. The latter was washed with water or dilute caustic solution until neutral, dried,

mesa-te 'andstripped'to a temperature or *'200- ;225-- 'C. -=-at 5 mm. pressure.

The results :of "tests of "yariousaproperties of esters prepared ioythev above general method are atomsand between eaeh=-1pair-=or said non-carbon atoms, the 'total number or carbon atoms and said non-carbonatoms in each of the radicals R1, R2, R3, and R4 being irom to' "and the shown'in,thestollowingttable: 5 total'number'of suliur-atoms ineach-radical be- 'AlmenMachine Kinematic i 'WVtsZCariid Viscosity 1 Vis 7 Grag l ag i Flash rom as'im g Reacmms Point Slope f ffigg;

V a i a 1 3 E 100 F. 210 F. Alone Mineral 2'nioi's1 o'o13..i; -5 1 mol Ethylene glycolnu. --.:55 63.590 8. 908 0. 677 120 14}. 4 mols 2-EthylhexanoL. Q: %m0%Si:g%]-e3 --i-l- 4 l we a, mo y no g yco 1' aim'olsiEthylenegglycolmonorn-i v 497 650 'lqsi butyl her.... 2 mols PO p l 1 11101 Triethylene glycol 27s -is rmwi --se;7so 0. 521 Lim n 4 mols Os 0x0 alcohol 1 2 mols P0013 i r 1 mol Triethylene gly 360 35 143. 1 19. 260 0. 559 133 12 4 mols Butyl Oarb1to1 2 mols P0 O1: 1 mol Thiodiglycol 395 284. 9 30. 790 0. 545 127 13(?) 15 4 mols Os 0x0 alcohol 1 conventionally refined Coastal naphthenic oil of 40 seconds Saybolt viscosity at 210 F. The unblended oil base carried only two weights on the Almeu machine.

The above data indicate that the esters con- 3 ing not greater than '2; and in which the comstituting the subject matter of the present invention possess characteristics, particularly with regard to viscosity index, pour point and load carrying capacity, which indicate their suitability for general use as lubricating oils and particularly for use where the presence of additives is not desirable. The esters of the present invention may also be blended with mineral lubricating oils to give lubricants of improved viscosity index and pour point. The esters may also be employed as grease bases and as plasticizers.

What is claimed is:

1. As a new composition of matter a compound oi the formula where R is an organic radical selected from the group consisting of (1) saturated aliphatic hydrocarbon radicals of 2 to 18 carbon atoms and (2) radicals consisting of a series of saturated aliphatic hydrocarbon groups linked through at least one non-carbon atom of the group consisting of oxygen and sulfur, each such hydrocarbon radical so linked containing at least 2 carbon atoms, the total number of carbon atoms and said non carbon atoms in the entire radical being from 5 to 80, and the number of sulfur atoms in the radical being not greater than 2; where R1, R2, R3, and R4 are organic radicals selected from the group consisting of (1) allphatic hydrocarbon radicals containing -1 to: 20 carbon atoms and (2) radicals consisting of a series of saturated aliphatic hydrocarbon radicals linked through 1 to 5 non-carbon atoms of the group consisting of oxygen and sulfur, there being at least 2 carbon atoms between each phosphate group and the nearest of said non-carbon where R is a series of saturated aliphatic hydrocarbon groups iinked through at least one oxygen atom, each hydrocarbon radical so iinked by an oxygen atom containing at least 2 carbon atoms, the total number of carbon and oxygen atoms in the entire radical being from 5 to 80, where R1, R2, R3, and R4 each represent a radical consisting of a series of saturated aliphatic hydrocarbon radicals linked through 1 to 5 oxygen atoms, there being at least '2 carbon atoms between each phosphate group and the nearest of said oxygen atoms and between each pair of said oxygen atoms, the total number of carbon and oxygen atoms in each of the radicals R1, R2, R3, and R4, being from 4 'to 20, and where the components of the composition are so chosen that the molecular weight thereof is at least 300.

3. As a new composition of matter a compound of the formula in which R1, R2, R3, and R4 each represent a radical consisting of a series of saturated aliphatic hydrocarbon radicals linked through 1 to 5- oxygen atoms, there being at least '2 carbon atoms between each phosphate group and the nearest of said oxygen :atoms and between each pair ofsaid oxygen atoms, the total number of carbon and oxygen atoms in each of the radicals being from 4 to 20, and in which the components of the composition are so chosen that the molecular weight thereof is at least 300.

4. A composition according to claim 1 in which R1, R2, R3, and R4 each represent a 2-ethy1hex'yl radical.

5. A composition according to claim 3 in which I R1, R2, R3, and R4 each represent the radical --CH2CH2OC4H9 6. A composition according to claim 2 in which R of the formula represents the radical 20 '7. A composition according to claim 2 in which R of the formula represents the radical (CH2CH2O) 2CH2CH2- and in which R1, R2, R3, and R4 each represents the radical PAUL V. SMITH, J R. FRED KNOTH, J R.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 2,411,671 Smith Nov. 26, 1946 FOREIGN PATENTS Number Country Date 555,192 Great Britain Aug. 10, 1943 OTHER REFERENCES lxudvik et al., J. Econ. EntomoL, Vd. 40, pp. 97-100 (1947). 

1. AS A NEW COMPOSITION OF MATTER A COMPOUND OF THE FORMULA 